1. Field of the Invention
The present invention relates to magnetic disk apparatuses which are used as external recording units for computers and the like and, more particularly, to a magnetic-head slider support mechanism for pressing or urging a magnetic head slider, with a minute force, in a direction toward a surface of a magnetic disk, and a magnetic recording apparatus into which the magnetic-head slider support mechanism is incorporated.
2. Related Art And Prior Art Statement
As disclosed in Japanese Patent Unexamined Publication No. 55-22296, a usual or conventional magnetic head slider is supported by a support mechanism which is arranged such that an arm having a length of about 15 to 25 mm and a mechanism element which is called a pivot and a gimbal, which has a torsional rigidity of about 20 gfmm/rad and which is substantially rotatable are joined to each other at a forward end of the arm, and is so arranged as to fly in air above a magnetic disk.
Further, as disclosed in Japanese Patent Unexamined Publication No. 62-99967, a visco-elastic membrane or film in the form of a diaphragm is utilized to support a slider under a rotatable state.
By the way, in recent years, development of a magnetic head slider which runs under a state in which the magnetic head slider is in contact with a surface of the magnetic disk or fly in liquid, in order to reduce a spacing between a magnetic head and the magnetic disk to achieve high recording density has been desired.
FIG. 7 of the attached drawings schematically shows a state where a curved-surface slider of a contact running type is loaded or mounted on the above-described conventional or prior art support mechanism which has a rotary mechanism at the forward end of the arm. A magnetic head slider 2 is arranged such that a recording and reproducing element 4 most approaches a disk surface under a state or condition in which a magnetic disk 3 is stationary. In the case, however, where the magnetic head slider 2 is subjected to a frictional force by rotation of the disk or by seek operation of the magnetic head slider, the magnetic head slider 2 is rotated to result in a spacing loss .DELTA.h for the reason that the magnetic head slider 2 has a rotary mechanism 5d whose torsional rigidity is about 20 gfmm/rad. In the case where the radius of curvature of the slider curved surface is 1 mm, the height of the slider is 0.5 mm and the frictional force is 0.3 gf, .DELTA.h amounts to about 30 nm, so that recording and reproducing operation is made impossible. Moreover, the running speeds are varied in inner and outer peripheries of the disk. Furthermore, since presence and absence of the seek operation, the speeds and the accelerations vary as the case may be, .DELTA.h is not constant so that steady recording and reproducing cannot be problematically effected.
Furthermore, FIG. 8 is a schematic view in the case where the rotary mechanism is provisionally removed in the above-described prior art. Also, in this case, the magnetic head slider 2 is arranged such that the recording and reproducing element 4 most approaches the disk surface under a state where the magnetic disk 3 is stationary (a designed position in FIG. 8). However, owing to the upward and downward movements (fluctuation) of the disk surface produced during rotation of the disk, a spacing loss .DELTA.h is generated between the recording and reproducing element 4 and the disk surface, as shown in FIG. 8 in the case where the disk surface is moved, for example, downwardly. For this reason, there is a problem that recording and reproducing at high recording density cannot be practiced stably.
In this manner, when the curved-surface slider of a contact running type is loaded on the prior art support mechanism having the rotary mechanism at the forward end of the arm, the magnetic head slider is rotated relative to the guide arm by the frictional force and the fluctuation of the disk surface. Thus, the recording and reproducing element is spaced away from the magnetic disk surface.
Further, the prior art which utilizes a visco-elastic film in the form of a diaphragm has also a torsional rigidity of the same level of that of the prior art which has the rotary mechanism, and is so designed as to be substantially rotatable with respect to the magnetic disk. Accordingly, even if the curved-surface slider is loaded on the prior art, a similar problem is generated.
Moreover, according to these prior arts, a spring constant of the support mechanism in a direction, in which the magnetic head slider is urged against the magnetic disk surface is about 1-2 mg/.mu.m. Normally, the magnetic disk surface is moved upwardly and downwardly (fluctuation) 10 .mu.m by the rotation of the magnetic disk. Accordingly, variation of the urging force becomes 20 mg. In the case where a full or total load is equal to or lower than 100 mg or so, a ratio of variation becomes equal to or higher than 20%. Thus, the stable head running is impossible.
Meanwhile, in order to reduce the spring constant in the urging direction in the aforesaid prior art, it is required in the case of Japanese Patent Unexamined Publication No. 55-22296 to increase a length of the support mechanism 10. In this case, the torsional rigidity is further reduced, and the rigidity in the other direction is reduced, so that a bad influence is exerted also upon the seek operation of the magnetic head slider, that is, upon the time of operation of movement in a radial direction of the disk. This is not preferable. In the case where the visco-elastic film in the form of the diaphragm is utilized, it is required to reduce the thickness of the visco-elastic film, or to enlarge the diameter thereof, in order to reduce the spring constant in the urging direction. However, also in that case, an influence of the tension force acting within the surface of the visco-elastic film acts largely. Accordingly, it is extremely difficult to reduce the spring constant.
Furthermore, the support mechanism having a rotary mechanism at the forward end of the arm as shown in FIG. 7 is used in such a manner that the arm which generates a load and the gimbal supporting the slider under a rotatable state are joined to each other by welding and the like. This is not preferable in view of assembling easiness, assembling accuracy, cost and the like.